As we predicted almost exactly a year ago, the annual changeover of clocks to daylight saving time, which takes place this weekend, has occasioned yet another outpouring of attacks on the institution. Among them this time around is this emblematic screed by Mark Joseph Stern of Slate.com.
Our defense of DST still holds, and there’s no more appropriate moment to reprint it than right now. The following column ran originally on March 12, 2018. Please remember to set your clocks to spring ahead at 2 a.m. Sunday morning.
Twice a year, like clockwork — so to speak — pundits fill the news columns with assaults on daylight saving time. It makes people groggy, even gives them heart attacks, they say. It’s an anachronism from the time when America was an agrarian country, and unnecessary in the modern world.
You’ve probably come across all these arguments lately, because they land when daylight saving starts and when it ends. On Sunday morning at 2 a.m., America sets its clocks ahead by an hour, launching the period of daylight saving that will end in eight months, or Nov. 3, when the clocks fall backward by an hour.
The trophy for the most comprehensive attack on DST probably belongs to the Atlantic, in which Matt Schiavenza called it “wasteful, cruel and dangerous” in 2015. Schiavenza collected all the familiar raps on DST without making very clear that they’re all equivocal. He also failed to make clear that most of the raps on DST apply to the day or days following the switchover, not to the eight-month period in which the time difference is in effect.
That’s important because some of the reported effects are in conflict. Some studies detect a spike in traffic accidents in the first days after the spring change, especially that first Monday, when people theoretically are still feeling the effects of being deprived of up to an hour’s sleep.
But studies also show a significant drop in traffic fatalities over the entire daylight saving period. The reason is that motorists are driving in daylight, not dusk or darkness, during the evening hours; the improved visibility makes the roads safer.
Other statistics mustered to attack daylight saving time exude the distinct aroma of bogosity. Schiavenza cites a survey purporting to find $434 million in lost productivity from the lost hour of sleep on the post-switchover Monday. Schiavenza takes this figure as gospel. It’s hard to see why. It turns out that the statistic is based on a survey done for Carpenter Co., a manufacturer of “comfort cushioning” — that is, pillows.
Carpenter’s marketing pitch is that more sleep is good for everyone, so buy its pillows. As for the productivity loss, it’s calculated by adding up the cost of heart attacks, workplace injuries in the mining and construction sectors, and increased “cyberloafing,” whatever that is. “A reasonable economic cost was then developed from the economic costs of heart attacks, workplace accidents and cyberloafing,” the survey firm says.
We’ve seen these sorts of numbers before. They include calculations of the lost productivity from March Madness bracket-picking, password-changing, fantasy football, etc., etc. These aren’t real calculations, but extrapolations based on hopelessly murky assumptions. They’re press-release parlor games, and obviously shouldn’t be taken seriously.
The most commonly cited purported result from the DST switchover involves heart attacks. Supposedly these spike on the Monday after the spring change.
A few things need mentioning about this finding, such as it is. First, it’s based on a single study published by a group of Swedish researchers in 2013. Every reference to heart attack traces back to this study. I could find no effort to replicate or validate its findings anywhere in the medical literature.
Furthermore, the study was limited to a database maintained by Blue Cross Blue Shield of Michigan of cardiac patients treated within that state. The researchers acknowledged that the phenomenon might apply only regionally, not nationally.
Most important, the researchers noticed that the overall incidence of myocardial infarction for the week following the spring switchover didn’t change at all — there were more cases on Monday, but fewer in the rest of the week. Most reporting on the study glides obliviously over this key fact.
One consequence of the twice-yearly attention on daylight saving time is that it encourages even intelligent people to ponder ever more baroque solutions to the global time-keeping “problem.” On Sunday, for example, Benjamin Wittes, editor in chief of the indispensable Lawfare blog, proposed via Twitter that the entire world convert to Universal Time, or UTC.
This essentially would put everyone on Greenwich Mean Time — when it’s 7 a.m. in that British town, it would be 7 a.m. everywhere. But 7 a.m. would mean something different to you, depending where you are. In Los Angeles, you might be just drifting off to sleep, because although the bedside clock would read 7 a.m., it would be what we think of today as midnight. A salaryman in Tokyo might be just starting to think about where he’ll pop in for an after-work drink, because it would be today’s 4 p.m.
“There is no reason — except sentiment — why 700 am needs to be morning or that 11:00 pm needs to be late evening,” Wittes tweeted.
Except there is a reason. It’s that convention, or “sentiment” as Wittes would have it, gives us the most efficient signal of conditions in time zones not our own. Say it’s 11 a.m. in Los Angeles, and you want to make a call to Tokyo. You ask Google or Alexa one question: “What time is it in Tokyo?” When the answer comes back, “3 a.m.,” you know it might not be a great idea to place the call just then.
If we were on UTC and the answer were to come back, “11 a.m.,” you wouldn’t know anything. You’d still have to ask, “What are they doing in Tokyo — snoring, commuting, out on a date?”
Coordinating time across great distances is an old problem. Most people may not know that the current system of time zones at one-hour variants only dates from 1883, when the U.S. railroad industry needed an alternative to the labyrinth of local times, often set by towns or villages, that made a hash of railway timetables. At noon in Philadelphia, according to a card that travelers could keep on their persons in 1862, the time was 10:59 a.m. in St. Louis, 11:10 in Chicago, 12:04 p.m. in New York, 12:06 in Albany, and 12:16 in Boston. The railway guide compiling all these variations ran to 200 pages.
It took years for the railroads to develop the new system, but only a few weeks for it to become accepted nationwide as the official switchover date (Nov. 18, 1883). The same thing happened with daylight saving time: It was first proposed by Ben Franklin in 1784, implemented nationwide by Franklin Roosevelt in 1942, and made permanent, with an opt-out for individual states, in 1966.
Since then, DST has worked pretty durn well. DST adds an hour of sunlight to our most active period of the day, from mid-afternoon to evening, giving the average 9-to-5 worker a bit more time to enjoy life under natural light. Popular Mechanics calls DST “a human attempt to force our lives to fit the natural world in a more sensible way, to lifehack ourselves into a pattern of living that benefits our minds and bodies. DST is both a rebellion against the clock and an acceptance that we are all slaves to the clock.”
You think it’s disruptive to spring ahead or fall backward twice each year? Think about the adjustments you’d have to make if you lost an hour of that spring and summertime daylight.